Skip to main content

Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

See other formats


MIDDLE OILS  (GAS OILS)

349

American and Russian petroleums of D 0-780 dissolve respectively in 5-2
and 4-1 c.c. of the solvent, and fractions of D 0-820 in 9-5 and 4-5 c.c. respec-
tively of the solvent.

*
* *

A good lamp oil should be clear and only slightly coloured (in time, however,
darkening occurs if the oil is exposed to the air) ; its odour should be neither
too penetrating nor unpleasant, as this would indicate the presence of sulphur
compounds.1 It should have no appreciable acidity and should not turn brown
with sulphuric acid. For use in cold places, it should remain clear and mobile
at a temperature lower than that to which it is likely to be exposed. The
specific gravity is usually 0-780-0-805 for American and 0-0820-0-825 for Russian
oils.

With regard to fractional distillation, a good oil should not begin to distil
below 110 and should contain only small amounts of light and heavy oils. The
limits usually demanded for ordinary lamp oils are 5% of light oils and 10%
of heavy oils, but the proportions actually present are well within these limits
for good oils. As regards the fractions comprised between 150 and 300,
there should be no great disproportion between the amounts of these and the
middle fractions should predominate over the extreme.

The flash point is of importance as an indication of the danger attending
the use of the oil. In Italy, legislation demands that the flash point for lamp
oil, determined by the Abel-Pensky apparatus, should not be below 21 C.

The viscosity of lamp oil, measured by the Engler apparatus at 20 C., is
1-1-05, r. measured by the Ubbelohde apparatus, 1-10-1-80, and is usually
somewhat lower for Russian than for American oils.

The illuminating power varies with the lamp used, but, under ordinary con-
ditions, the consumption per candle-hour at 15-20 varies from 3-5 to 5 grams.
The decrease in luminosity from the beginning to the end of the combustion
is generally greater with American than with Russian petroleums. The latter
burn with a less initial and greater final luminosity than the former. In any
case, with a good oil the decrease should not exceed one-fourth of the initial
value.

Lamp oils from crude petroleums rich in solid paraffin, e.g., those from
Boryslav, Pennsylvania, etc., if not properly prepared, deposit solid paraffin
at  10, but those of Russian origin remain clear even at  20.

The calorific power of lighting oil is 11,000-12,000 cals.

MIDDLE   OILS

(Gas Oils)

These are intermediate in character to lighting oil and heavy oils. They
are mobile and yellow to dark brownish-yellow, their density being between
about 0-845-0-855, their b.pt. 300-350, and their viscosity below 3 (Engler).

The most important determination with these oils is the yield of gas
and the calorific value of the latter. The amount of gas given is determined
in a small works plant. In the laboratory it may be ascertained approxi-
mately, in comparison with a typical oil, in Ross and Leather's apparatus,2

1 According to Kissling and Engler (Chem. Rev. Fett. 2nd., 1906, p. 158), the pro-
portion of sulphur in Russian petroleums lies between 0-027 and 0-030% ; in Galician,
between 0-039 and 0-062% ; in Pennsylvanian, between 0-027 and '029%> and- in
those from Ohio, between 0-04 and 0-5%. A good oil should not contain more than

0-03%.

z Journal of Gaslighting, 1906, p. 825., 270, p. 233.0